Printing plates suitable for offset lithographic printing are known which comprise a support having a surface having non-image areas which are hydrophilic and image areas which are hydrophobic and ink-receptive.
The art of lithographic printing is based upon the immiscibility of oil and water, wherein the oily material or ink is preferentially retained by the image area and the water or fountain solution is preferentially retained by the non-image area. When a suitably prepared surface is moistened with water and an ink is then applied, the background or non-image area retains the water and repels the ink while the image area accepts the ink and repels the water. The ink on the image area is then transferred to the surface of a material upon which the image is to be reproduced; such as paper, cloth and the like. Commonly the ink is transferred to an intermediate material called the blanket which in turn transfers the ink to the surface of the material upon which the image is to be reproduced.
Ink-jet printing is a non-impact method for producing images by the deposition of ink droplets on a substrate in response to digital signals.
JP-A-53015905 describes the preparation of a printing plate by ink-jetting an alcohol-soluble resin in an organic solvent onto an aluminium plate.
JP-A-56105960 describes the formation of a printing plate by ink-jetting onto a support e.g. an anodised aluminium plate an ink capable of forming an oleophilic image and containing a hardening substance such as epoxy-soybean oil together with benzoyl peroxide, or a photo-hardening substance such as an unsaturated polyester.
A method of preparing printing plates using the ink-jetting technique is required which avoids the use of organic solvents and/or light-sensitive materials.